The following includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art, or relevant, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.
Today, pain has become the universal disorder, a serious and costly public health issue, and a challenge for family, friends, and health care providers who must give support to the individual suffering from the physical as well as the emotional consequences of pain. In general, there are two basic types of pain, acute and chronic. Acute pain, for the most part, results from disease, inflammation, or injury to tissues. This type of pain generally comes on suddenly, for example, after trauma or surgery. In some instances, it can become chronic. Chronic pain is widely believed to represent disease itself. Chronic pain persists over a longer period of time than acute pain and is resistant to most medical treatments. It can, and often does, cause severe problems for patients.
Arthritis is considered to be one of the most pervasive diseases in the United States and a leading cause of disability. According to the Centers for Disease Control and Prevention, it is estimated that 1 of every 3 Americans is affected by one or more of the more than 100 types of arthritis. Pain, particularly of the joints throughout the body, characterizes arthritis. Psoriasis, primarily a skin disorder, can progress to psoriatic arthritis if left untreated. Rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis are all examples of degenerative arthritic diseases.
In addition to, for example, arthritic causes, normal function of a joint and its movement, and other portions of the body, can be severely impaired as a result of trauma or following orthopedic and other surgical procedures. This may result in tenderness, aching, pain, and lengthy recovery times, as well as loss of joint mobility or reduced range of motion, tonicity, or elasticity of the joint/articular structures, such as for example, muscle, tendon, capsule, bone, or ligament. Reduced joint mobility may also involve permanently altered or shortened joint or tissue architecture. Altered or abnormal joint mobility or joint architecture may also be associated with or caused by a variety of injuries and conditions such as, for example, metabolic disorders, ischemia, injury to joint, capsule, bone, cartilage, tendon, ligament or muscle, fractures, subluxation, dislocation, crush injuries, prolonged immobilization (e.g., immobilization of a joint in a cast or splint), and paralysis.
When non-pharmacological measures are not sufficient to control the symptoms of osteoarthritis, current evidence-based guidelines support pharmacological treatment with acetaminophen or oral nonsteroidal anti-inflammatory drugs (“NSAID”s) (American College of Rheumatology Subcommittee on Osteoarthritis Guidelines. Recommendations for the medical management of osteoarthritis of the hip and knee: 2000 update. Arthritis Rheum. 2000; 43:1905-15; National Collaborating Centre for Chronic Conditions. Osteoarthritis: National clinical guideline for care and management in adults. London: Royal College Physicians, 2008. Available at: http://www.nice.org.uk/nicemedia/pdf/CG059FullGuideline.pdf.; Zhang W, et al., Osteoarthritis Cartilage 2007; 15:981-1000; Zhang W, et al., Osteoarthritis Cartilage 2008; 16:137-62. Acetaminophen has been linked with an increased risk of hepatic, hypertensive and cardiovascular adverse effects (e.g., Chan A T, et al., Circulation. 2006; 113:1578-87. Epub 2006 Mar. 13; Pincus T, et al., Ann Rheum Dis. 2004; 63:931-9).
NSAIDs are more effective (Towheed T E, J Rheumatol. 2006; 33:567-73) and carry more well-known gastrointestinal and cardiovascular risk (e.g., Antman E M, et al. Use of nonsteroidal anti-inflammatory drugs: an update for Clinicians: a scientific statement from the American Heart Association. Circulation. 2007; 115:1634-42; Chan A T, et al. Nonsteroidal anti-inflammatory drugs, acetaminophen, and the risk of cardiovascular events. Circulation. 2006; 113:1578-87). The attempt to minimize the risk of both morbidity and potential mortality by prescribing COX-2 selective NSAIDs (‘coxibs’) has not achieved the goal (Kearney P M, et al. BMJ. 2006; 332:1302-8; Mamdani M, et al., BMJ. 2004; 328:1415-6).
Diclofenac is used, most commonly, as the sodium or potassium salt for relief from pain and inflammation such as musculoskeletal and joint disorders including rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis. U.S. Pat. Nos. 4,575,515 and 4,652,557 disclose topical NSAID compositions, one of which, consisting of 1.5% diclofenac sodium, 45.5% dimethylsulphoxide (“DMSO”), ethanol, propylene glycol, glycerine, and water, has been shown to be effective in the treatment of chronic osteoarthritis (e.g., Towheed, Journal of Rheumatology 33:3 567-573 (2006); Oregon Evidence Based Practice Center entitled “Comparative Safety and Effectiveness of Analgesics for Osteoarthritis,” AHRQ Pub. No. 06-EHC09-EF).
The skin provides a protective barrier against foreign materials and infection. In mammals this barrier is created primarily by the outermost epidermal layer, the stratum corneum. The stratum corneum is comprised of flat, extended, enucleated cells, termed corneocytes, the periphery of which comprises a highly insoluble protein and lipid structure, called the cornified envelope (“CE”), surrounded by lipids. (Downing et al., Dermatology in General Medicine, Fitzpatrick, et al., eds., pp. 210-221 (1993); Ponec, M, The Keratinocyte Handbook, Leigh, et al., eds., pp. 351-363 (1994)). The CE is composed of polar lipids, such as ceramides, sterols, and fatty acids, and a complicated network of cross-linked proteins; however, the cytoplasm of stratum corneum cells remains polar and aqueous. The stratum corneum is extremely thin (some 20 microns) but provides a substantial barrier. Nevertheless, the skin has been considered as a route for the administration of drugs. Various transdermal delivery systems achieve epidermal penetration by using a skin penetration enhancing vehicle.
Topical NSAIDs present a safer potential alternative to oral therapy, with decreased systemic exposure to the active NSAID molecule. While previous reviews (Mason L, et al., BMC Musculoskelet Disord. 2004; 5:28) have suggested that topical NSAIDs are effective for osteoarthritis, Lin et al. (BMJ. 2004; 329:324-6) in their metaanalysis of the same studies stressed that the various products showed symptom relief at 1 or 2 weeks but loss of benefit at 4 weeks, and rejected them as there was insufficient evidence to justify a recommendation of long-term use.
Subsequently published randomized controlled studies have described a penetrating topical diclofenac solution in a dimethyl sulfoxide (DMSO)-containing vehicle as efficacious and safe in relieving the symptoms of primary osteoarthritis of the knee over 4-, 6-, and 12-week treatment periods (Baer P A, et al. BMC Musculoskelet Disord. 2005; 6:44; Bookman A A, et al. CMAJ. 2004; 171:333-8; Roth S H, Shainhouse J Z. Arch Intern Med. 2004; 164:2017-23; Tugwell P S, et al. J Rheumatol. 2004; 31:2002-12). Recent topical NSAID reviews and meta-analyses (Banning M., Br J Community Nurs 2006; 11:487-92; Banning M., Expert Opin Pharmacother 2008; 9:2921-9; Biswal S, et al., J Rheumatol. 2006; 33:1841-4; Haynes S, Gemmell H., Clinical Chiropractic 2007; 10:126-38; Moore R A, et al., Rheum Dis Clin N Am 2008; 34:415-32; Ozguney I, Expert Opin Pharmacother 2008; 9:1805-16; Towheed T E, J Rheumatol. 2006; 33:567-73; Zacher J, et al., Current Medical Research and Opinions 2008; 24(4):925-950) have evaluated the data from these topical diclofenac solution studies, and subsequently published national guidelines (Chou R, et al. Comparative Effectiveness and Safety of Analgesics for Osteoarthritis. Comparative Effectiveness Review No. 4. Rockville, Md.: Agency for Healthcare Research and Quality. September 2006. Available at: www.effectivehealthcare.ahrq.gov/reports/final.cfm; National Collaborating Centre for Chronic Conditions. Osteoarthritis: National clinical guideline for care and management in adults. London: Royal College Physicians, 2008. Available at: http://www.nice.org.uk/nicemedia/pdf/CG059FullGuideline.pdf; Tannenbaum H, et al., J Rheumatol. 2006; 33:140-57; Zhang W, et al. 2007, supra; Zhang W, et al. 2008 supra) have cited these studies as evidence for the use of topical NSAIDs as first line therapy for osteoarthritis. Topical diclofenac solution is used for the treatment of osteoarthritis and is currently approved for sale in Canada and several European countries.
The efficacy of topical NSAIDs, such as topical diclofenac solution, is thought to be due to local action of the active NSAID molecule following its penetration through the skin to the tissue sites of inflammation and pain. Diclofenac sodium is a member of the arylacanoic acid group of NSAIDs with lipophilic properties that limit its percutaneous penetration (Nishihata T, et al., Chem. Pharm. Bull 1987; 35:3807-12). The biological property of DMSO to enhance skin penetration of both hydrophilic and lipophilic molecules is known (Williams A C, Barry B W, Adv Drug Deliv Rev 2004; 56:603-18), with recent research focusing on the mechanism of enhancement (Gurtovenko A A, Anwar J, J Phys Chem B 2007; 111:10453-60). The percutaneous absorption of diclofenac following a multidose regimen of a topical diclofenac solution (based on a DMSO-containing vehicle) was significantly enhanced compared to an aqueous diclofenac formulation without DMSO (Hewitt, P G, et al., Pharmacol Res. 1998; 15:988-92). Within the extensive literature on DMSO are unsubstantiated claims of therapeutic efficacy in the treatment of osteoarthritis, but no efficacy of DMSO vehicle was shown in a previous, 4-week randomized controlled study of a topical diclofenac solution (Bookman A A, et al. Effect of a topical diclofenac solution for relieving symptoms of primary osteoarthritis of the knee: a randomized controlled trial. CMAJ. 2004; 171:333-8).
There remains a need in the art for methods of dosing topical diclofenac formulations, and providing users and prescribers with information regarding drug product attributes and desired therapeutic effects as well as instructions on uses in conjunction with other topical agents. Such needs are met by the inventions and discoveries provided herein.